Hitherto, as an optical disk in which stereoscopic moving picture is recorded, and its reproducing device, the structure as shown in FIG. 10 is known. Herein, in an optical disk 201, right-eye signals are recorded alternately in even-field regions 204, 204a, 204b, and left-eye signals, in odd-field regions 203, 203a, 203b. When such optical disk 201 is reproduced by an existing optical disk reproducing device 205 as shown in FIG. 11, the right-eye images and left-eye images appear on a TV 206 alternately in every 1/60 second. With the naked eye, only the right-eye and left-eye images appear to be a duplicate image. However, when observed through stereoscopic goggles 207 for changing over the right-eye and left-eye shutters once in every 1/60 second, a stereoscopic image is seen. As shown in FIG. 12, the right-eye image and left-eye image are alternately encoded in every field in the interlace signals in one GOP (Group of Pictures) of MPEG signal. As high-quality videos, the progressive system is being studied.
Problems in the prior art are discussed. When a conventional stereoscopic optical disk is reproduced in a standard reproducing device, an ordinary image which is not stereoscopic image, that is, 2D image is not delivered. A stereoscopic optical disk cannot be reproduced by a reproducing device unless a stereoscopic display is connected thereto. It was hence necessary to fabricate two types in the same contents, that is, a stereoscopic optical disk and a 2D optical disk. It is the same for high-quality videos. That is, the conventional stereoscopic and high-quality optical disks were not compatible with ordinary videos. A purpose of the invention is described below. It is a purpose of the invention to present a mutually compatible stereoscopic and high-quality optical disk and a reproducing system. As the definition of compatibility is clarified, the compatibility may be just compared to the relation between the monaural record and stereo record in the past. That is, a new stereoscopic optical disk is reproduced as a mono-vision, that is, 2D with an existing reproducing device, and is reproduced as either mono-vision or stereo-vision, that is, stereoscopic video with a new reproducing device.